Mesalamine is also known as mesalazine, 5-aminosalicylic acid, and 5-amino-2-hydroxybenzoic acid, and has the following structural formula:

Mesalamine is an anti-inflammatory that is often used to treat inflammatory bowel disease such as ulcerative colitis and Crohn's disease.
Mesalamine is commercially available in the United States under a variety of trade names and dosage forms such as CANASA® (suppository), ROWASA® (enema), DELZICOL® (delayed release capsule), APRISO® (extended release capsule), PENTASA® (extended release capsule), ASACOL® and ASACOL® HD (delayed release capsule), and LIALDA® (delayed release tablet). Some patents that have been identified as covering these commercial mesalamine products include U.S. Pat. Nos. 5,541,170; 5,541,171; 6,551,620; 6,649,180; 6,773,720; 6,893,662; 7,645,801; 8,217,083; 8,337,886; 8,436,051; 8,496,965; 8,580,302; 8,865,668; 8,911,778; 8,940,328; 8,956,647; and 9,089,492.
It is believed that mesalamine is topically active in the lower gastrointestinal region and in particular in the terminal ileum, colon, and rectal region. Therefore, oral dosage forms are designed to release the mesalamine in these regions, usually by use of a delayed release coating, sometimes referred to as an enteric coating. Some oral dosage forms have also attempted to provide a controlled release of mesalamine in the target regions by employing a controlled release excipient in conjunction with the delayed release coating. However, these controlled/delayed release dosage forms have problems. For example it has been discovered that the LIALDA® product, which employs a tablet core matrix comprising mesalamine and sodium carboxymethylcellulose that is coated with an enteric coating, exhibits a faster release of the drug after storage under accelerated conditions, such as at 40° C. and at 75% relative humidity. This storage fluctuation may have adverse effects on drug release because it may cause large amounts of the drug to be released prematurely, i.e. released not at the target area, or excess amounts of the drug released too fast in the target area which may lead to adverse effects such as major fluctuations of therapeutic levels of the drug between dosing intervals.
The amount of mesalamine dosed orally is often very high. For example, the dosing for the LIALDA® tablet is two to four tablets administered once a day, wherein each tablet contains 1.2 grams (1200 mg) of mesalamine. Due to the large dosing requirements, the formulation of solid oral dosage forms of mesalamine is difficult because the amount of excipients that may be incorporated into a tablet or capsule must be kept to a minimum to allow the dosage form to be easily swallowed, and to keep the number of dosage forms per administration to a minimum number, i.e. less than 4 dosage forms per administration.